Reply by Gene Howe

I use two fences. One is a manufactured one that stays parallel and, one is shop made and does not stay parallel. As you surmise, since the bit travels in a circular path perpendicular to the table, a parallel fence is of no consequence.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton